Currently, various types of display devices are used for various uses. In a general display device, one pixel is formed of three sub pixels respectively for displaying red, green and blue, which are three primary colors of light. Owing to this, color display is made possible.
However, a conventional display device has a problem that the range of displayable colors (referred to as the “color reproduction range”) is narrow. FIG. 25 shows a color reproduction range of a conventional display device which provides display using three primary colors. FIG. 25 is an xy chromaticity diagram of an XYZ colorimetric system, and the triangle defined by three points, acting as apexes, corresponding to the three primary colors of red, green and blue represents the color reproduction range. In the diagram, colors of various objects existent in the natural world (see Non-patent Document 1) revealed by Pointer are plotted with “x”. As understood from FIG. 25, there are colors which are not encompassed in the color reproduction range, and a display device for providing display using the three primary colors cannot display the colors of a part of the objects.
Thus, in order to broaden the color reproduction range of the display device, techniques have been proposed to increase the number of primary colors used for display to four or greater.
For example, Patent Document 1 discloses a liquid crystal display device 800 in which, as shown in FIG. 26, one pixel P is formed of six sub pixels R, G, B, Ye, C and M respectively for displaying red, green, blue, yellow, cyan and magenta. FIG. 27 shows a color reproduction range of the liquid crystal display device 800. As shown in FIG. 27, the color reproduction range represented by the hexagon defined by six points, acting as apexes, corresponding to the six primary colors nearly encompasses the colors of the objects. As seen from this, the color reproduction range can be broadened by increasing the number of primary colors used for display.
Patent Document 1 also discloses a liquid crystal display device in which one pixel is formed of four sub pixels respectively for displaying red, green, blue and yellow, and a liquid crystal display device in which one pixel is formed of five sub pixels respectively for displaying red, green, blue, yellow and cyan. By using four or more primary colors, the color reproduction range can be made broader than that of the conventional display device for providing display using the three primary colors. In this specification, display devices for providing display using four or more primary colors will be collectively referred to “multiple primary color display devices”, and a liquid crystal display device for providing display using four or more primary colors will be referred to a “multiple primary color liquid crystal display device”.